When the brake lever on a bike is pulled, the brake pads clasp the wheel rim and create friction, thus stopping the bicycle. Our experiment tests the frictional force that two different types of bicycle brakes apply to the wheel rim. We tested both V-Brakes and Caliper Brakes. In a V-Brake, or a linear pull brake, a cable pulls on two arms which connect the brake pad to the rim, stopping the bike. Caliper Brakes have one arm that pivot the center while another arm pivots on the side. Both types of brake are commonly found in bikes. We wanted to discover which type of bicycle brake is more efficient. In other words, on which brake do you have to exert more force to stop the bike?
V-Brake
Procedure
In our experiment, we first attached the bicycle to a bike repair stand. Next, we tied a piece of string to a spoke on the wheel 20 cm away from the hub and used tape to prevent sliding. Then, we attached another piece of string to the end of the brake lever of the corresponding wheel. We tied loops on the end of each piece of string and fastened force sensors linked in with Logger Pro to each loop.
On the computer, we zeroed the force meters while the strings were unattached. One person applied 5 Newtons of force with the brake lever sensor while the other pulled on the force sensor attached to the wheel, keeping the spoke with the string tied to it perpendicular to the ground, and the string parallel to the ground. The person pulling the brake lever sensor made sure to pull it in the direction of the brake lever's rotation and to not let the string touch the handlebars. Meanwhile, we ran Logger Pro and recorded the point at which the wheel moved. We repeated this for 10, 15, and 20 Newtons of force on the brake lever.
Results
Best Fit Lines For Caliper Brakes and V-Brakes
Conclusions
After analyzing our data, we concluded that the stopping force that V-Brakes apply is much greater than the stopping force of the Caliper Brake. There is a point of intersection in the graph, however, which suggests that the brakes work with equal efficiency at a certain point of speed. The majority of the time though, the V-Brakes are more powerful with less force applied to the lever. This information is useful because it could help bike manufactures decide which type of brake to mount on certain types of bikes. It takes a lot more braking power to stop a mountain bike than a road bike, so bicycle manufacturers should mount V-Brakes on mountain bikes and Caliper Brakes on Road Bikes.
However, our experiment did have limitations. The force sensors were limited to 50 Newtons of force, so we couldn't apply more than 20 Newtons to the brake lever. Also, the sensors were incredibly precise and therefore difficult to keep at one measurement when pulling on the brake lever. Due to the sensors' precision we weren't able to take very specific data. In addition, the force needed to stop the bike is also dependent on other factors, such as the speed at which the bike is traveling and the person riding the bike. Our experiment is also only using two bicycles, so some bikes might have stronger and more efficient Caliper brakes and some bikes might have V-Brakes with shorter arms, decreasing the mechanical advantage. In future experiments, people could test other types of brakes, or determine how the force applied to different brakes is influenced by the speed of the bike. However, this would be hard to test with force sensors.
Table of Contents
Bicycle Brakes
Erich, Ben
Introduction
When the brake lever on a bike is pulled, the brake pads clasp the wheel rim and create friction, thus stopping the bicycle. Our experiment tests the frictional force that two different types of bicycle brakes apply to the wheel rim. We tested both V-Brakes and Caliper Brakes. In a V-Brake, or a linear pull brake, a cable pulls on two arms which connect the brake pad to the rim, stopping the bike. Caliper Brakes have one arm that pivot the center while another arm pivots on the side. Both types of brake are commonly found in bikes. We wanted to discover which type of bicycle brake is more efficient. In other words, on which brake do you have to exert more force to stop the bike?Procedure
In our experiment, we first attached the bicycle to a bike repair stand. Next, we tied a piece of string to a spoke on the wheel 20 cm away from the hub and used tape to prevent sliding. Then, we attached another piece of string to the end of the brake lever of the corresponding wheel. We tied loops on the end of each piece of string and fastened force sensors linked in with Logger Pro to each loop.On the computer, we zeroed the force meters while the strings were unattached. One person applied 5 Newtons of force with the brake lever sensor while the other pulled on the force sensor attached to the wheel, keeping the spoke with the string tied to it perpendicular to the ground, and the string parallel to the ground. The person pulling the brake lever sensor made sure to pull it in the direction of the brake lever's rotation and to not let the string touch the handlebars. Meanwhile, we ran Logger Pro and recorded the point at which the wheel moved. We repeated this for 10, 15, and 20 Newtons of force on the brake lever.
Results
Best Fit Lines For Caliper Brakes and V-Brakes
Conclusions
After analyzing our data, we concluded that the stopping force that V-Brakes apply is much greater than the stopping force of the Caliper Brake. There is a point of intersection in the graph, however, which suggests that the brakes work with equal efficiency at a certain point of speed. The majority of the time though, the V-Brakes are more powerful with less force applied to the lever. This information is useful because it could help bike manufactures decide which type of brake to mount on certain types of bikes. It takes a lot more braking power to stop a mountain bike than a road bike, so bicycle manufacturers should mount V-Brakes on mountain bikes and Caliper Brakes on Road Bikes.However, our experiment did have limitations. The force sensors were limited to 50 Newtons of force, so we couldn't apply more than 20 Newtons to the brake lever. Also, the sensors were incredibly precise and therefore difficult to keep at one measurement when pulling on the brake lever. Due to the sensors' precision we weren't able to take very specific data. In addition, the force needed to stop the bike is also dependent on other factors, such as the speed at which the bike is traveling and the person riding the bike. Our experiment is also only using two bicycles, so some bikes might have stronger and more efficient Caliper brakes and some bikes might have V-Brakes with shorter arms, decreasing the mechanical advantage. In future experiments, people could test other types of brakes, or determine how the force applied to different brakes is influenced by the speed of the bike. However, this would be hard to test with force sensors.
References
Zenn, Lennard. Zinn and the Art of Road Bike Maintenance 2nd edition. Bolder: VeloPress, 2005.V-Brake Picture
Caliper Brake Diagram
How V-Brakes work